According to a conventionally known technique, example, a flange made of Kovar is brazed to a ceramic, and a pipe member made of a metal is connected to the flange 2 from inside by means of silver solder (Patent Document 1).
According to this technique, the pipe member has a circumferential groove formed at an end portion thereof. The groove obstructs a flow of a molten silver solder so as to prevent flow of the molten silver solder into unnecessary portions, whereby the molten silver solder can be concentrated at a brazing zone for firm brazing.